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Alpha longitudinal (work in progress)

Alpha longitudinal lets openpilot take full control of the gas and brakes, instead of Mazda's stock radar cruise.

stock alpha radar AEB · FCW live PCM gas · brakes AEB stays armed vision model drives end to end long planner zoompilot alpha PCM gas · brakes radar off

Safety features disabled

If alpha longitudinal is enabled, the car's radar is turned off. Automatic Emergency Braking (AEB) and Forward Collision Alerts are DISABLED while alpha longitudinal is on.

If this trade-off is not acceptable to you, do not enable alpha longitudinal.

Credit: Alex Frutkin (@yummydirt) did the reverse engineering and implementation for this feature.

What changes with alpha longitudinal

  • openpilot controls acceleration and braking end to end.
  • Cruise features such as Smart Cruise and Speed-Limit Assist work the same way as with the stock radar.
  • In experimental mode, zoompilot uses the openpilot model end to end and can brake for stop signs and lights.

Known limitations

  • Experimental models do not often accelerate to the set speed.
  • Stop and go is improved but not totally fixed. Cruise may disengage after stopping for a lead car.
  • Expect dash errors and safety issues. This is a work in progress.

Dash errors while on alpha longitudinal

If your dashboard throws cruise, LKAS, or radar errors:

  1. Turn the car completely off.
  2. Leave it off for 15 minutes so the ECU resets.
  3. Drive again.

See also Troubleshooting.

Availability

  • 2022+ CX-5: supported since the first zoompilot release.
  • CX-9 and EPS-swapped models: supported since 2026.08.25.

See Supported cars.

Design details

The measurement record behind the longitudinal port — radar takeover and hand-back, the CRZ_INFO checksum, stop-and-go, MRCC state semantics — is in Mazda longitudinal.